In an interview with Greta Van Susteren, Mitt Romney blamed teachers unions for the problems with American schools and, in particular, pointed out that California's school decline was because of unions.
Mitt Romney said that America’s schools have gotten worse because “we’ve basically given our school system to the teachers unions.” As an example, he pointed to California, noting, “it used to have some of the best schools in the country, and now it’s ranked near the very bottom.”
Think Progress points out that the real culprit is tax cuts:
Specifically, a ballot initiative enacted in 1978 called Proposition 13 that capped property taxes, which were, at the time, the primary funder of public schools. As the Santa Monica, California-based think tank The Rand Corporation noted:
"Indeed, Proposition 13 marked a dramatic turning point in funding for K–12 public education in California. Revenues and expenditures per pupil had grown fairly rapidly both in California and nationwide until the early 1980s. But California fell well behind the nation by the late 1980s. Despite recent funding increases for K–12 education, California schools have continued to spend far below the national average. Measured in year 2000 dollars, spending per pupil in California went from more than $600 above the national average in 1978 to more than $600 below the national average in 2000."
For Romney's claim to be valid, there would have to be some correlation between states with weak unions and strong student performance and vice versa. The weakest unions tend to be in "right-to-work" (for less) states, which include: Alabama, Arizona, Arkansas, Florida, Georgia, Guam, Idaho, Indiana, Iowa, Kansas, Louisiana, Mississippi, Nebraska, Nevada, North Carolina, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia and Wyoming.
Ten of the worst 11 states in terms of low graduation rates are "right-to-work" states. Similarly, 7 of the 9 worst states in terms of math and science scores are "right-to-work" states. Six of the 10 worst states in terms of SAT scores are 'right-to-work' states. I could go on, but the point is obvious that the states with the weakest unions, which also tend to be the states that spend the least on education, are also the states that tend to produce the worst results in terms of education outcomes.